DESCRIPTION (Applicant's Abstract): The long-term objectives of this proposal are to characterize the physiological, biochemical and pathological changes that occur in the maxillary sinuses of individuals with clinically diagnosed chronic sinus disease. The hypotheses are based on the observation that nitric oxide is present in high concentrations in the nose of normal individuals but not in sinusitis patients. We hypothesize that, in response to a viral and/or bacterial infection, ciliated epithelial cells lining the sinus generate cytokines. There follows an infiltration of activated inflammatory cells, mainly neutrophils that generate superoxide. In the unique environment of the sinus, i.e. high nitric oxide concentration, the superoxide free radical preferentially reacts with nitric oxide to generate the highly cytotoxic peroxynitrite species rather than with its natural scavenger, superoxide dismutase. We suggest that the ensuing free radical cascade injures the ciliated epithelium. These events, together with the detritus in the sinuses, result in a decreased synthesis and increased absorption of nitric oxide in chronic sinus disease. To test these hypotheses, sinus mucosa will be studied from control and chronic sinusitis patients undergoing elective surgery. Catheritization of the maxillary sinus and the introduction of various concentrations of NO at varying flow rates will allow a determination of the rates of nitric oxide production and absorption in situ, Further, the determination of ciliary beat frequency during these procedures (using a specially designed laser Doppler probe) will demonstrate the relationship between ciliary function and NO concentrations. In vitro studies of sinus mucosa and sinus lavage fluids, using tonometry, NO metabolite analysis and enzymology, will further characterize these processes. Immunohistochemical staining of resected sinus tissues and archival tissue paraffin blocks will allow an identification of the NOS isoforms and their distribution in healthy and diseased tissues as well as the amounts and properties of the enzymes (Western blots, Elisa assay and enzymatic techniques using highly specific NOS antagonists). In addition, the techniques previously described will be used to determine nitro tyrosine resides, nitrosylated proteins and markers of apoptosis. CDNA array analysis for 400 cell related RNAs will give further insights into the pathogenesis of chronic sinusitis and results from these assays will suggest which specific cell signaling agents need further quantification by ELISA. Animal studies suggest a relationship between NO-induced cell injury and immune-complex/ autoimmune diseases. Understanding these processes in the human sinus promises to provide new seminal information that could result in new therapy, better management and even prevention of chronic sinus disease.